Add a section for about:logging in our user docs

Currently we don't have any documentation related to `about:logging`. It would be good to add that. It's especially useful for Android profiling as it has more in-device profiling capabilities.

┆Issue is synchronized with this [Jira Task](https://mozilla-hub.atlassian.net/browse/FP-1422)

Start in the user documentation and locate the existing sections about profiling workflows and Android support. Use about:logging as the subject and describe its in-device profiling capabilities for Android; the work is done when users can find a clear, useful section covering this workflow.

Written by the indexing model from the issue text.